Superheated Water


Put simply, superheating involves raising the temperature of a liquid, for instance, beyond its boiling point without allowing it to vaporize. This can be done by heating water in a sealed container above 100 Celsius. There is an urban myth that has done the rounds for many years that it is possible to superheat the contents of a liquid-filled cup in a microwave and trigger a geyser of fluid when you remove it and stir. Who hasn’t received the spam-mail describing the 26-year old who was severely disfigured by such an incident?

Well, there are risks associated with all cooking, and heating a liquid in a microwave for long enough will produce a boiling temperature liquid and a container surface coated with scalding hot “condensation” that could cause you to jolt and end up splashing yourself with scalding liquid.

Apparently, it happens, so be careful. However, I think it would be hard to actually “superheat” the liquid, although the guys in this video may have done just that using pure, distilled water or similar.

The liquid would have have no so-called “nucleation” points, specks of dust, particles, or whatever, even scratches inside the beaker to seed bubbles of steam. The water could very easily surpass its boiling point without actually boiling.

Like Snopes says, it is possible but takes a lot of effort to cause superheating in a normal cup under normal conditions in a microwave oven. Nevertheless, it’s not worth risking a scalding in an attempt to duplicate the above experiment with your morning coffee.


10 thoughts on “Superheated Water

  1. Well,
    I was heating up water for a cup of tea and the microwave oven door burst open with a bang, water water everywhere! I googled it and confirmed the theory that the water in my cup had become super heated. Particulars: I’d heated the water for about 2 minutes earlier, then forgot about it, when I remembered, about 20 minutes later, it had cooled to the point that I figured my tea wouldn’t steep well, so I set the timer for 3 minutes, all the while talking with one of my co-workers, I thought that the water was taking quite awhile to heat up, no boiling, no bubbling, nothing, then suddenly, boom! the door flew open and water was everywhere. It was in a ceramic cup, about 3/4 full bottled drinking water. I didn’t touch it, didn’t add anything to it, just plain ole undisturbed water heating up in a regular old clean coffee cup in a regular old microwave oven. SH*T happened… big wet mess. Fortunately no’one was in the path of the super heated water as it flew from the microwave.

  2. Hello. I have one question for you. What will happen if I pour in some super heated water in super cooled water.. what could happen. I am a student at Physics in Romania and I am going to try making this experiment and study some proprieties during the process of instant freezing. Waiting for some opinions.

  3. Roger, sounds like your wife was very lucky…but…why on earth was she heating a glass of water in the microwave oven, and for that long, four and a half minutes? Jeeez, it was bound to do something dramatic, I’d use a kettle in future, it’s what they’re designed for…

  4. My wife put about 1 and 3/4 cups of water heating in a pyrex glass measuring cup,into the microwave. She heated it about four and a half minutes.When she opened the door and took the water out it exploded. I was in the other room and heard the explosion. Sounded like a twelve gauge going off. The water all came out the cup severly burning her right arm. Thank god it didn’t hit her face. She has first to second degree burns on her arm. This was water straight from the faucet.Her clothing kept her leg from getting really burned. I have used microwaves for over 30 years and have never witnessed this before.

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